Lovely photos, they are obviously at home, if your happy with them in your pond & garden then they are a nice addition, I wonder why she isn't nesting.

An amusing aside regarding Mallards, we have a good number at Whinfell Center Parcs where I now work, David Cameron having made my environmental business cease to be viable with the changes to the agricultural environmental grant schemes.

Last winter we had a lot of complaints about how dirty the entrance to the visitors centre was on the side away from the lake. The problem was obviously duck poo, but ducks don't go into the visitors centre, or we didn't think they did. Then late at night a group of Mallards were observed aproaching the automatic doors & flapping their wings. When the doors opened they marched inside & settled down for the night. In the morning they got up went to the doors flapped their wings & walked out when they opened.
Staff were tired of hosing down the entrance & it looked bad to guests who were up & about early so one night 4 members of staff went in with a net & caught them. On counting it turned out that there were:

1 Male
1 Juvenile
11 Females

Obviously with Mallards the female are the more intelligent sex.

The ducks caught were taken to a farm a few miles away that had a pond, their wing feathers were clipped so that they couldn't fly till they moulted & got new wing feathers & they were then released to settle into their new home.